The invention generally relates to hermetic scroll compressors and more particularly to check valves for preventing the reverse flow of refrigerant through the scroll compressor which may occur upon stopping compressor operation. When compressor operation is stopped and the orbiting scroll member is no longer driven so as to orbit about the fixed scroll member, a reverse pressure differential occurs resulting in the reverse flow of refrigerant which urges the orbiting scroll member to move in the reverse direction. This causes undesirable noise.
U.S. Pat. No. 5,088,905 (Beagle) discloses a scroll compressor check valve which includes a valve member and a support member positioned directly adjacent the scroll discharge port for preventing reverse scroll operation upon compressor shutdown. A problem associated with this design is that with the check valve located outside of the scroll mechanism undesirable noise is realized outside of the compressor. In addition, with the valve positioned in the discharge chamber, response time is adversely affected because of the large volume of discharge gas associated with the discharge chamber.
U.S. Pat. No. 4,560,330 (Muriyama et al) discloses a scroll compressor having a spring biased fluid check valve disposed in a refrigerant suction passageway which moves to an open position during compressor operation so as to allow refrigerant to communicate through an intake pipe to the suction chamber defined by scroll members. During compressor shutdown the fluid check valve moves to a closed position so as to prevent reverse flow of refrigerant from the suction chamber back into the intake pipe thereby preventing reverse scroll member rotation. A problem associated with the Muriyama design is that during compressor startup and while the compressor is running energy must be expended to act against the spring bias to open and hold open the check valve. In addition, this design is sensitive to dirt jamming the piston valve.
Problems associated with earlier check valve assemblies include heightened expense related to complex spring biased and multi-part assemblies, noise generated by valves in the discharge chamber snapping into place, sluggish reaction time, and lower efficiencies to name a few.